tasks a-s

Task/Roman-numerals-Decode/PL-SQL/roman-numerals-decode.sql

@@ -0,0 +1,83 @@
+/*****************************************************************
+ * $Author: Atanas Kebedjiev $
+ *****************************************************************
+ * PL/SQL code can be run as anonymous block.
+ * To test, execute the whole script or create the functions and then e.g. 'select rdecode('2012') from dual;
+ * Please note that task definition does not describe fully some current rules, such as
+ * * subtraction - IX XC CM are the valid subtraction combinations
+ * * A subtraction character cannot be repeated: 8 is expressed as VIII and not as IIX
+ * * V L and D cannot be used for subtraction
+ * * Any numeral cannot be repeated more than 3 times: 1910 should be MCMX and not MDCCCCX
+ * Code below does not validate the Roman numeral itself and will return a result even for a non-compliant number
+ * E.g. both MCMXCIX and IMM will return 1999 but the first one is the correct notation
+ */
+
+DECLARE
+
+FUNCTION rvalue(c IN CHAR) RETURN NUMBER IS
+    i INTEGER;
+BEGIN
+    i := 0;
+    CASE (c)
+        when 'M' THEN i := 1000;
+        when 'D' THEN i := 500;
+        when 'C' THEN i := 100;
+        when 'L' THEN i := 50;
+        when 'X' THEN i := 10;
+        when 'V' THEN i := 5;
+        when 'I' THEN i := 1;
+    END CASE;
+    RETURN i;
+END;
+
+
+FUNCTION decode(rn IN VARCHAR2) RETURN NUMBER IS
+   i  INTEGER;
+   l  INTEGER;
+   cr CHAR;   -- current Roman numeral as substring from r
+   cv INTEGER; -- value of current Roman numeral
+
+   gr CHAR;   -- next Roman numeral
+   gv NUMBER; --  value of the next numeral;
+
+   dv NUMBER; -- decimal value to return
+BEGIN
+           l := length(rn);
+           i := 1;
+           dv := 0;
+           while (i <= l)
+           LOOP
+                cr := substr(rn,i,1);
+                cv := rvalue(cr);
+
+   /* Look for a larger numeral in next position, like IV or CM
+      The number to subtract should be at least 1/10th of the bigger number
+      CM and XC are valid, but IC and XM are not */
+                IF (i < l) THEN
+                   gr := substr(rn,i+1,1);
+                   gv := rvalue(gr);
+                   IF (cv < gv ) THEN
+                      dv := dv - cv;
+                   ELSE
+                      dv := dv + cv;
+                   END IF;
+                ELSE
+                   dv := dv + cv;
+                END IF;  -- need to add the last value unconditionally
+
+                i := i + 1;
+            END LOOP;
+
+RETURN dv;
+
+END;
+
+BEGIN
+
+    DBMS_OUTPUT.PUT_LINE ('MMXII      = ' || rdecode('MMXII'));       -- 2012
+    DBMS_OUTPUT.PUT_LINE ('MCMLI      = ' || rdecode('MCMLI'));       -- 1951
+    DBMS_OUTPUT.PUT_LINE ('MCMLXXXVII = ' || rdecode('MCMLXXXVII'));  -- 1987
+    DBMS_OUTPUT.PUT_LINE ('MDCLXVI    = ' || rdecode('MDCLXVI'));     -- 1666
+    DBMS_OUTPUT.PUT_LINE ('MCMXCIX    = ' || rdecode('MCMXCIX'));     -- 1999
+
+END;